Regulatory Matters (Tables)

12 Months Ended

Dec. 31, 2017

Regulated Operations [Abstract]

Schedule of Actual Capital Amounts and Ratios

The actual capital amounts and ratios are presented in the table below:

	Actual				For Capital Adequacy Purposes				To Be Well Capitalized  Under Applicable Action Provisions
($ in thousands)	Amount		Ratio		Amount		Ratio		Amount		Ratio
As of December 31, 2017:
Total Capital (to Risk Weighted Assets)
Enterprise Financial Services Corp	$	589,047	12.21	%	$	385,816	8.00	%	$	—	—	%
Enterprise Bank & Trust	546,314		11.36		384,791		8.00		480,989		10.00
Tier 1 Capital (to Risk Weighted Assets)
Enterprise Financial Services Corp	496,045		10.29		289,362		6.00		—		—
Enterprise Bank & Trust	503,312		10.46		288,593		6.00		384,791		8.00
Common Equity Tier 1 Capital (to Risk Weighted Assets)
Enterprise Financial Services Corp	428,397		8.88		217,021		4.50		—		—
Enterprise Bank & Trust	503,264		10.46		216,445		4.50		312,643		6.50
Leverage Ratio (Tier 1 Capital to Average Assets)
Enterprise Financial Services Corp	496,045		9.72		204,087		4.00		—		—
Enterprise Bank & Trust	503,312		9.68		207,885		4.00		259,856		5.00
As of December 31, 2016:
Total Capital (to Risk Weighted Assets)
Enterprise Financial Services Corp	$	506,349	13.48	%	$	300,573	8.00	%	$	—	—	%
Enterprise Bank & Trust	430,981		11.53		298,982		8.00		373,728		10.00
Tier 1 Capital (to Risk Weighted Assets)
Enterprise Financial Services Corp	412,865		10.99		225,430		6.00		—		—
Enterprise Bank & Trust	387,497		10.37		224,237		6.00		298,982		8.00
Common Equity Tier 1 Capital (to Risk Weighted Assets)
Enterprise Financial Services Corp	357,729		9.52		169,072		4.50		—		—
Enterprise Bank & Trust	387,461		10.37		168,178		4.50		242,923		6.50
Leverage Ratio (Tier 1 Capital to Average Assets)
Enterprise Financial Services Corp	412,865		10.42		158,480		4.00		—		—
Enterprise Bank & Trust	387,497		9.81		157,933		4.00		197,417		5.00